A ringback tone is an audible indication that is heard on the telephone by a caller while the destination device (the callee) is being rung. Standard ringback tones are relatively simple sounds, such as a tone, that are repeated to the caller. Ringback tones are designed to assure the caller that the line of the callee is ringing.
Some telephone service providers allow subscribers to define custom ringback audio. The custom ringback audio may include, for example, a portion of a song. Further, telephone service provides may allow the subscriber to choose different custom ringback audio for different callers. For example, a subscriber may specify a group of callers, such as those corresponding to the subscriber's family, that should hear custom ringback audio, while all other callers may hear the standard ringback tone.